This article is taken from the Dec. 26, 2012, digital edition of Commercial Property Executive. It was written by Brad Berton, a contributing writer for the publication.
While gathering information for an issue of AWCI’s TechUpate, I came across some interesting information about new types of insulation with higher R values than the current products on the market. In view of the ever-increasing requirements of the Department of Energy to reduce energy consumption in buildings, I felt the need to pass my thoughts to our members. Some of you may have encountered these insulation materials, but I am sure many of you have not. While the new products offer benefits not currently available, they do have drawbacks you need to be aware of.
The three discussed in the article, which was published Dec. 26, 2012, by Commercial Property Executive and written by Brad Berton, a contributing writer for the publication—were vacuum insulation panels (VIPs), silica aerogels and phase-change materials (PCMs). The following is an explanation from the article about the three types:
“VIPs currently in the development stage cannot boast quite the structural flexibility of aerogel-embedded insulation products they can offer exceptional thermal performance at a more attractive cost. The latest products often offer R-40 (per inch of thickness) or better thermal protection, compared to just R-4 with many traditional mineral fiber insulation alternatives. As for the physical composition, modern building insulation VIPs’ core glass microfiber matrix materials—most often fumed silica—are encapsulated within a vacuum-sealed enclosure envelope with metal (mostly aluminum or aluminized) skins.”
“Experts foresee considerable longer-term promise for aerogels, which are billed as the lightest and best insulating solid on Earth and have been used to encase equipment on Mars Explorers. While the new insulating products are flexible, the actual encapsulated aerogel materials are solids composed of particles (derived from gels; hence the name) that are 90 to 99 percent air. These materials, dubbed ‘frozen smoke,’ almost entirely nullify the primary methods of heat transfer: convection, conduction and radiation.”
“PCMs, which have proven dramatically effective in European office demonstrations, are more of an energy storage technology than a purely thermal barrier material. The trick behind PCMs is that their encapsulated solutions absorb heat as they liquefy at the desired daytime temperature then releases it when they solidify as temperatures cool at night.”
My main goal in investigating these products was to find an insulation material that would satisfy the requirements of the International Energy Conservation Code as well as a thinner product than EPS, XPS or polyiso to reduce the overall thickness of the wall assembly. As with any new product, it will have pluses and minuses. While not all of these three types of insulation are currently on the market, I do not think it will be long before we start to see them.
While the VIP panels look appealing from the standpoint of the R value and a thickness of 1 inch, they are currently available only in small panels. Cost is another factor with a price of $5 to $7 per square foot. The initial cost is high but when considering the payback time of four years or less, the cost can be justified. A bigger problem in using this material is the vacuum part. If the panel is punctured, vacuum is lost. Producers claim that even when deflated the panel still provides an R-7. While the producers have engineers working on the problem, I do not think this material would not work well in a stucco assembly when you consider that the lath is required to be attached by 7 inches on center.
Next on the list are aerogels. Aerogels are billed as the lightest and offer a high R value. The material is rather stiff. While the actual thickness was not discussed in the article, they are thinner than VIP materials and also more costly at $10 per square foot. Products composed of aerogels are currently available from several suppliers and are available in flexible blankets. All things considered this may well be an ideal insulation material for a stucco assembly. One product being marketed is a 3/8 inch x 1 1/2 inch strip. Its prime purpose is to eliminate the thermal break found on steel studs. A big problem with applying insulation on the outside of the studs in a stucco assembly is the thicker the insulation, the longer the fastener. For example, when using 4 inches in the assembly, the fastener would be 5 1/2 inches long and would have to be a number 10 screw. Anything less than a number 10 will cam out before penetrating the steel stud.
The last material is PCM. PCMs are best suited for climates that experience hot days and cold nights. The claim is that PCMs will reduce peak loads by 40 to 45 percent during the day and 60 to 70 percent at night. Some manufacturers are using PCMs embedded in plaster, ceiling tiles, drywall panels and aerated concrete. A problem with PCMs is its fire retard-ability. While they said costs are also a problem, the article did not state the actual price tag. I would have to see more data before I can suggest that you use PCMs in a stucco assembly.
Donald E. Smith, CCS, is AWCI’s director of technical services. Send your questions to email@example.com, or call him directly at (703) 538.1611.